The present invention relates to a block copolymer, and more particularly to a block copolymer with a distinguished moldability, which can be simply and economically produced even from rework products or recycle products, and which is also capable of producing moldings distinguished in rigidity at high temperatures, heat resistance, chemical resistance, surface appearance, etc.
Polyamides, polyesters, polycarbonates and polyarylates are known as engineering plastics and are widely used as materials for various parts in the versatile consumer goods fields including packaging, containers, etc., the automobile field, the electric and electronic field, the machinery and industrial product field, the office-equipment field, the aviation and space development field, etc.
To attain higher integration and higher weight, demands for substituting engineering plastics for metallic materials have been recently much intensified in these various fields of part materials, and as a result the performance level required for the engineering plastics has been made much higher. Specifically, resin materials having an appearance substitutable for the metallic materials and applicable to severe circumstances such as excessive exposure to heat, light, chemicals, etc. have been keenly desired. From the environmental viewpoint, on the other hand, the spur to reuse moldings and parts of the engineering plastics as rework or recycle products has been also intensified.
To meet these intensified demands for the engineering material characteristics, methods for blending mixtures of different kinds of resin components with a compatibilizing agent by melt kneading, that is, polymer alloy technology, have been so far studied to improve their performances while making up for disadvantages of single resin materials. It is well known that the materials based on the polymer alloy technology have been already commercially available.
However, in improvement of the compatibility of different kinds of thermoplastic resins, the polymer alloy technology still suffers from economical problems such as requirements for special compatibilizing agents and for modification of molecular structures of resins per se.
To overcome the above-mentioned problems, a more economical and easier method than the polymer alloy technology, that is, a method using mixtures of different kinds of resin components together with a reaction catalyst has been now under study. Specifically, U.S. Pat. No. 4,417,032 discloses a method for producing a somewhat random copolymer by melt-blending two or more kinds of homopolymers of polyamide in the presence of a phosphite ester compound. U.S. Pat. No. 4,417,031 discloses a method for producing graft and/or block copolymers by reaction of two or more kinds of homopolymers of polyamide, polyester and xcex2-unsaturated carboxylic acid. JP-A-6-62846 discloses a method for melt-blending polyamide with polyester in the presence of an arylphosphoryl azide compound. Japanese Patent No. 2,721,479 discloses a resin composition comprising a mixture of polybutylene terephthalate having a specific viscosity with polyester, and a specific phosphorus compound. Furthermore, Japanese Patent No. 2,999,546 discloses a method for adjusting a melt flow rate by mixing a mixture of at least two kinds of thermoplastic resins selected from polyamide, polyester, polyarylate, etc. with a filler such as glass fibers, etc. followed by melt kneading under reduced pressure.
All of the above-mentioned prior arts comprise controlling the compatibility of resin mixtures on the basis of exchange reactions of polyamide-polyamide, polyamide-polyester, polyester-polycarbonate, etc. According to the present inventors"" study, control of the exchange reactions has not yet been satisfactory, so that the intensified demands for the engineering material characteristics in various uses have not been satisfied. It is under the present status that their development into various uses is considerably restricted.
The present invention has been established to overcome the above-mentioned problems, and an object of the present invention is to provide a block copolymer having a distinguished moldability for forming various parts, etc., and which is producible from rework products or recycle products as raw materials and also capable of producing moldings distinguished in rigidity at high temperatures, heat resistance, chemical resistance, surface appearance, etc.
As a result of intensive studies to attain the object of the present invention, the present inventors have successfully found that the object of the present invention can be attained by using a block copolymer comprising specific polymer components and having a specific relation between the glass transition temperatures of the individual polymer components and the glass transition temperature of the resulting block copolymer, and have established the present invention.
That is, the present invention includes the following aspects [1]-[18] of the invention.
[1] A block copolymer comprising at least two kinds of polymer components each having a different structural unit in the polymer, (B) a phosphite ester compound and (C) a phosphite metal salt and/or a hypophosphite metal salt, where the polymer components are melt kneaded with the components (B) and (C), where the polymer components are selected from the group consisting of polyamide, polyester, polycarbonate and polyarylate, Y given by the following formula (1) is 0.1-0.9:   Y  =                    1        m            ⁢              ∑                  j          =          1                m              ⁢          xe2x80x83        |                            Tg          j                -        X                              Tg          j                      (            A            )                          -        X              |  
(wherein m is the number of glass transition temperatures of the block copolymer, Tgj is the glass transition temperature (xc2x0 C.) of the block copolymer, Tg(A)j is the glass transition temperature (xc2x0 C.) of the polymer component nearest to Tgj among the glass transition temperatures of the polymer components, and X is given by the following formula (2):   X  =            ∑              i        =        1            n        ⁢                  Tg                  (          B          )                    ⁢              iw        i            
wherein n is the number of polymer components, Tg(B)i is the glass transition temperatures (xc2x0 C.) of the individual polymer components and wi is the weight ratios of the individual polymer components).
[2] A block copolymer as described in said [1], wherein the difference in the glass transition temperature between the polymer components constituting the block copolymer is 50xc2x0 C. or higher.
[3] A block copolymer as described in said [1], wherein the block copolymer has a weight average molecular weight (Mw) of 20,000-200,000.
[4] A block copolymer as described in said [1], wherein the block copolymer comprises at least two kinds of polyamides.
[5] A block copolymer as described in said [1], wherein the block copolymer comprises polyamide and polyester.
[6] A block copolymer as described in said [1], wherein the block copolymer comprises at least two kinds of polyesters.
[7] A block copolymer as described in said [1], wherein the block copolymer comprises polyester and polycarbonate.
[8] A block copolymer as described in said [1], wherein the polyamide is selected from the group consisting of polycaprolactam, polyhexamethylene adipamide, polyhexamethylene dodecamide, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polyhexamethylene cyclohexylamide and their copolymers.
[9] A block copolymer, as described in said [1], wherein the polyester is selected from the group consisting of polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate.
[10] A block copolymer, as described in said [1], wherein the block copolymer has an average sequence length of 10-50 determined by nuclear magnetic resonance (13Cxe2x80x94NMR).
[11] A process for producing a block copolymer, which comprises melt kneading (A) at least two kinds of polymer components each having a different structural unit in the polymer and selected from the group consisting of polyamide, polyester, polycarbonate and polyarylate, with (B) a phosphite ester compound and (C) a phosphite metal salt and/or a hypophosphite metal salt.
[12] A process for producing a block copolymer, as described in said [11], wherein the polymer components (A) are at least two kinds of polyamides.
[13] A process for producing a block copolymer, as described in said [11], wherein the polymer components (A) are polyamide and polyester.
[14] A process for producing a block copolymer, as described in said [11], wherein the polymer components (A) are at least two kinds of polyesters.
[15] A process for producing a block copolymer, as described in said [11], wherein the polymer components (A) are polyester and polycarbonate.
[16] A process for producing a block copolymer, as described in said [11], wherein the proportion of the component (B) is 0.05-10 parts by weight and the proportion of the component (C) is 0.05-10 parts by weight on the basis of 100 parts by weight of the polymer components (A).
[17] A process for producing a block copolymer, as described in said [11], wherein a molecular weight-controlling agent (D) is further melt kneaded.
[18] A process for producing a block copolymer, as described in said [17], wherein the proportion of the component (D) is 0.05-10 parts by weight on the basis of 100 parts by weight of the polymer components (A).